you could do a grill block and a belly pan and noone would even know. Just get a big piece of coroplast and paint it, then use cable ties to secure it behind the grill (between the grill and radiator) so it won't affect the outside look of the car. The belly pan won't even be seen and those help a lot on the highway.
Also the way you drive makes a huge difference. keep it at the speed limit or just under and you will see a big difference if you were going above the speed limit before
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